It’s impossible to overstate the effect that Mitt Romney’s performance in the first presidential debate has had on conservatives and Republicans. The past four years have been a torment, as we’ve watched a committed left-wing activist grease the skids for America’s decline into a socialist state. Our TV screens have featured images of violent protests in Greece, Italy, and Spain as their socialist paper boats capsize.

Yet the Obama administration’s resolute march into that dead end has proceeded apace. There was a brief bloom of hope that the Supreme Court would save the country from the worst time bomb of the Obama presidency, but a late betrayal by a conservative justice extinguished it.

The past few weeks have been especially painful, as Mr. Obama seemed to gain traction in the polls and escape responsibility for the completely foreseeable results of his policies — economic enfeeblement, rising poverty and dependency, loss of world influence, and looming insolvency. More than that, a mendacious address by Bill Clinton blaming the economic meltdown of 2008 on free markets and Republicans seemed to be the only argument on offer — and one voters were inclined to accept.

The Romney campaign seemed to be missing in action. Increasingly desperate conservatives (this columnist included) begged him to improve his television ads, which were insipid and off-topic; they pleaded with him to “go big” and address the crisis the Obama presidency has created for the nation; and they warned that the Obama campaign’s lies about Romney’s tax proposals should not go unrebutted. Incredibly, polls were showing that voters trusted Obama more than Romney even on the matter of taxes, though Republicans are well known to be the party of tax cuts.

The feeling, on the right, was that the fate of the nation was really at stake; that due to a tendentious and corrupt press, an inattentive electorate, and a watery nominee, the country might be on the verge of an irreversible disaster — the reelection of an incompetent leftist ideologue. It was a nightmare.

So it was more than partisan glee that lifted our spirits when a supremely skilled, razor-sharp Romney sailed to victory over Obama in Denver. It was the release of years’ worth of pent-up frustration at the fact that Mr. Obama has skated by with platitudes, lies, misrepresentations, and “cool” — while the nation we love, still “the last best hope of earth,” seemed to be sliding toward the drain.

With a brilliant and nearly perfectly pitched performance, Mitt Romney highlighted Mr. Obama’s distortions and lies, sometimes with simple declarative sentences — “Virtually everything he just said about my tax plan is inaccurate” — and sometimes with humor. When Obama recited one of his favorite faux facts, that companies get “a tax break for shipping jobs overseas,” Romney, in one of his tidy and organized catalogue of corrections, responded, “You said you get a deduction for taking a plant overseas. Look, I’ve been in business for 25 years. I have no idea what you’re talking about. I maybe need to get a new accountant.”

The mythical tax break for shipping jobs overseas, a staple of Obama rhetoric for more than four years, is a perfect encapsulation of the story of this presidency. Obama seems to be identifying a problem — except that his description is false. And if it were true, why did Obama do nothing about it when his party controlled both houses of Congress? Yet he has repeated this falsehood, along with so many others, to rousing cheers and approval from a Nobel Prize–winning economist and most of the press. He has never been pressed on his serial dishonesty and low demagoguery. He has lied with impunity, until now.

On Wednesday night in Denver, Mitt Romney pulled the statue from its plinth. He did so without showing disrespect for the man or the office he holds. With calm command of the facts, he expertly punctured the inflated balloon of complacent self-regard that President Obama has become, all the while keeping his focus on the larger matter at hand — how to remove the strangling grip of the state from the economy’s neck.

One debate does not usually decide an election. Mr. Obama will doubtless arrive in New York better prepared on October 16. But Mitt Romney, in one quite dazzling performance, has transformed the image of the president and of himself. It was the absolute best presidential-debate performance I have ever seen — and it didn’t come a moment too soon.